Denmark on Thursday allowed refugees to move freely through its territory to Sweden after days of chaos when authorities closed ferry services and a motorway link with Germany in an attempt to stem an inflow of thousands of asylum seekers.

Denmark, whose government took out adverts in Lebanese newspapers to discourage migrants, emerged as the latest front in Europe's worst refugee crisis in decades as 3,200 people entered since Sunday, most trying to get to Sweden.

Sweden expects to receive 80,000 refugees this year and has more asylum seekers per capita than any other European nation thanks to a generous immigration policy allowing automatic permanent residency for Syrians.

Allowing the resumption of traffic on ferries and the motorway, Danish police said they had no power to detain refugees. That means that thousands will now travel on to Sweden to seek asylum.

"There are no other possibilities than to let them go free, and consequently we cannot keep them from travelling where they will," National Police Commissioner Jens Henrik Hojbjerg said.

Centre right Prime Minister Lars Lokke Rasmussen held talks with political leaders on Thursday in a second emergency meeting this week but did not announce concrete action.

"Germany, Denmark and Sweden are in an extraordinary situation and in that situation it is our task to live up to our international obligations," Rasmussen said afterwards.

"I don't think anyone, at least not me or the party leaders, as I have heard it, wants Danish police to use force in a very violent way," he said.

In Stockholm, Swedish Prime Minister Stefan Lofven said EU rules under which refugees should be registered in the country where they first arrive must be upheld and the decision to send refugees on to Sweden was "unfortunate".

Across the bridge

When not temporarily detained, the refugees marched or took trains to Copenhagen, which is a 35-minute ride from Malmo in Sweden across the Oresund Bridge.

Sweden's Migration Agency said 686 people had applied for asylum in Malmo since Sunday and more that 13,700 had arrived in the country in the past five weeks.

Both countries have a generous welfare system but Denmark has recently tightened immigration and citizenship rules, including cutting benefits for refugees by up to half in a bid to discourage them from staying here.

Sweden stands out in the Nordics as the exception. Denmark's tough refugee policy mirrors similar trends in Finland and Norway where right-wing anti-immigrant parties are on the ascendant and part of coalition governments.

Finland's centre-right government proposed increasing some taxes to help cover the costs of migrants coming into the country.

The Danish People's Party (DF), once on the political fringe, became the second largest parliamentary force after June's election, gaining popularity largely due to its anti-immigration and eurosceptic rhetoric.

Rasmussen's minority government depends on the party's support in parliament although his response to the crisis this week has not been anywhere near as strong as the DF would like.

"We are a country based on law and order," DF leader Kristian Thulesen Dahl told reporters. "Citizens of other countries must also be able to see that when they decide whether to use Denmark as a transit country in this asylum shopping which is going on ... We need control."

Refugees given lifts

Refugees have been streaming in by two routes from Germany -- crossing by train overland into Jutland, the western part of Denmark that is connected to continental Europe, or by ferries carrying trains that arrive in Lolland, an island linked by bridges to Zealand, where Copenhagen is located.

At Rodbyhaven, the landing point for the ferries, around 50 people gathered, most volunteers with water bottles, as three boats arrived during the day, a Reuters reporter saw.

No passport checks were made at Rodby on Thursday when passengers disembarked from ferries.

Akhmed, a 32-year-old from Copenhagen, said that like others he had come to give refugees a lift to Copenhagen.

"I could sit at home and count on other people doing it, but my conscience couldn't stand for it," Akhmed said.

One group of volunteers said they had been giving lifts to refugees for 48 hours now, leaving them at Copenhagen's central station rather than in Malmo, to avoid charges of human trafficking.

On Wednesday, authorities closed down the Jutland motorway after 300 refugees began walking along it, and suspended train ferries to Lolland. On Thursday the motorway reopened and most train ferry services resumed.

The refugees are part of a wave of migrants sweeping north through Europe, many escaping the war in Syria.

In Hungary, police said they detained a record 3,321 migrants on Wednesday and the interior ministry indicated it may declare a state of crisis next week.

Austria suspended train services with Hungary at least for the rest of Thursday because it cannot handle the volume of migrants.